What is the point of a stereo microphone?

[Throckmorton]

Why put a stereo microphone on a digital camera, DSLR, or camcorder? The left and right microphones are separated by an inch at most, which makes stereo totally useless. Obviously marketing would be one explanation, but there are even "professional" microphones that are stereo. I've googled and found very little discussion about this. This thread is the closest-- one guy talks about how he laughs at customers who want a "stereo" boom mic. http://www.dvxuser.com/V6/archive/index.php/t-20945.html

So why is "stereo" on a single microphone body or on a camera accepted as the norm by people who should have the common sense to realize that there is no separation between the channels?

Put the manufacturing cost into a single better mic please.

 

[Syborg1211]

Just because the mics aren't separated by a lot of distance, they can still be aimed in such a way to deduce left and right. Your ears aren't stereo because of the separation between them. It's due to the different directions your ears point.

 

[AnitaPeterson]

OP, it's painfully obvious that you have no idea how a stereo microphone operates, or what it does. Stereo separation makes a big difference, regardless of the actual distance between microphones.

You are also taking the discussion in that forum link out of context. The guy criticizes SURROUND boom mics, not stereo microphones.

Also, in this day and age, having 1080p video with crappy mono audio is an insult to viewers.

 

[corkyg]

The question has been adequately answered by Anita and Syborg. RIP

 

[glen]

Actually, multiple things give location cues.
These also vary in importance by frequency.
Important ones for humans:
Amplitude, and amplitude difference in each ear. Louder in the right ear, so the brain assume more to the right.
Relative phase difference in each ear. You brain can tell if the tone hit your right or left ear first and roughly the time difference. Your brain can make precise location from this.
Relative changes in tone make something perceived to move vertically because your brain will assume it is the same tone entering the ear canal from a higher or lower angle, which shifts the tone slightly.

I cannot think of a way in which the stereo effect can recreate horizontal sound location using 2 microphone less than an inch apart, unless the exact parameters of the play back system are known, and some very specific and specialized DSP processing algorithms are used. I am almost positive that this is a marketing gimmick.

 

[SecurityTheatre]

Actually, multiple things give location cues.
These also vary in importance by frequency.
Important ones for humans:
Amplitude, and amplitude difference in each ear. Louder in the right ear, so the brain assume more to the right.
Relative phase difference in each ear. You brain can tell if the tone hit your right or left ear first and roughly the time difference. Your brain can make precise location from this.
Relative changes in tone make something perceived to move vertically because your brain will assume it is the same tone entering the ear canal from a higher or lower angle, which shifts the tone slightly.

I cannot think of a way in which the stereo effect can recreate horizontal sound location using 2 microphone less than an inch apart, unless the exact parameters of the play back system are known, and some very specific and specialized DSP processing algorithms are used. I am almost positive that this is a marketing gimmick.

The reproduction of audio in a movie also doesn't take into account accurate phase differences in the sound. Nor does it very accurately portray the VERY subtle difference in the time from one channel to the other. That seems unlikely to me. The speed of sound at room temperature is 343 m/s. The distance between your ears is about 150mm. That makes for 350 microseconds travel time. That's faster than the standards 22khz sampling rate of the audio you're recording, so it's not measurable using modern recording techniques.

The only thing that it could possibly be used for is for directionality. And that's exactly what I believe it does.

 

[glen]

The reproduction of audio in a movie also doesn't take into account accurate phase differences in the sound. Nor does it very accurately portray the VERY subtle difference in the time from one channel to the other. That seems unlikely to me. The speed of sound at room temperature is 343 m/s. The distance between your ears is about 150mm. That makes for 350 microseconds travel time. That's faster than the standards 22khz sampling rate of the audio you're recording, so it's not measurable using modern recording techniques.

The only thing that it could possibly be used for is for directionality. And that's exactly what I believe it does.

Sorry if this sounds mean.
???? Movie audio isn't stereo. Very different psycho acoustic assumptions, recording, and playback models.
I’ll give you 350 µs or 0.00035 for time between ears, but 22kHz is 0.0000454, plenty of resolution. However, sampling rate has been 44kHz (0.0000227) since Philips and Sony published it in the Redbook standard in 1980.

Again, anything is possible, but I have yet to read a paper or hear (lol) a convincing argument on this being able to record stereo. Infact, it is widely know/accepted in the industry that 17 ( or 15 cm), the human head width, is the MINIMUM distance that will work.